Assessment of the values of total shifts angles and maximum subsidence angles in conditions of mining reserves of the Verkhnekamskoe deposit of potassiummagnesium salts

The safety assessment of objects developed by underground mining operations, as well as those planned for construction over developed sections of mine fields, is based on the calculation of expected deformations. For a reliable determination of the latter, in the absence of instrumental observations over the section of the mine field under consideration, the issue of substantiating the values of the angles of total displacement Ψ and maximum subsidence Θ is of great importance. At present, in practice, the angles Θ are not used explicitly, and fixed values of the angles Ψ do not always allow for a reliable calculation of the length of the semi-trough of displacement and, as a consequence, for a correct calculation of the expected deformations. Taking into account the above, the main objective of this work is to substantiate the angles Ψ and Θ for the conditions of development of the reserves of the Verkhnekamskoye potassium-magnesium salt deposit, and, if appropriate, to establish the dependencies that determine them. The study revealed that the angles of total displacements Ψ under conditions of homogeneity of the geomechanical system structure are not prone to significant changes over time and depend mainly on the parameter of the degree of loading of interchamber pillars C. The reason for the possible decrease in the values of Ψ under conditions of heterogeneity of the geomechanical system structure was found. It was determined that the values of the angles of maximum subsidence Θ may differ from 90º. The values are substantiated and mathematical models are established for the studied angles Ψ and Θ, and the coefficients of the condition of complete undermining are clarified.